Process for the control of bacteria in secondary oil recovery



United States Patent Edward 0. Bennett, 3623 Alberta Ave., Houston,Tex., and Edward B. Hodge, 2906 Oak, Terre Haute, Ind.

No Drawing. Filed Apr. 2, 1959, Ser. No. 803,560

2 Claims. (Cl. 2528.55)

Our invention relates to the control of sulfate reducing bacteria inwater flooding operations used in the secondary recovery of petroleumoils, and more particularly, to controlling such organisms byincorporating into the flooding water effective amounts of4ethyl-3,5-heptanedione dioxime.

US. Patent No. 2,839,467 lists many of the problems found in thesecondary oil recovery art and the means whereby some of these problemshave been solved. The problem of controlling sulfate reducing is everpresent and always diflicult, as the growth of the microorganism is notcontrolled by economically practicable amounts of many bactericidesgenerally utilized in bacterial control and the microorganisms sometimesbecome resistant to generally used bactericides.

We have now discovered that sulfate reducing microorganisms areeconomically controlled by the addition of 4-ethyl-3,5-heptanedionedioxime to the flooding water.

The usual procedure for the treatment of water to be utilized inflooding operations is to produce a concentrate of the bactericide inWater and then continuously inject this concentrate into the water to beused in flooding I operations at a rate which forms a desired dilutionof the bactericide. This is done prior to pumping water into theoil-bearing subterranean formation. Sampling and checking the water forsulfate reducing bacteria will show whether the chemical concentrationsneed to be raised or may be lowered to effect an elimination of sulfatereducing bacteria from the water.

Alternately, 4-ethyl-3,5-heptanedione dioxime utilized in our processmay be added to the oil-bearing formations periodically, for example,once a week as a high potency concentrate or the undiluted4-ethyl-3,5-heptanedione dioxime may be injected into the formation.

We have found that 4-ethyl-3,5-heptanedione dioxime is active againstsome strains of sulfate reducing bacteria in Water at concentrations aslow as about 2-5 p.p.rn. However, we often prefer to utilizeconcentrations in excess of 2-5 p.p.m., and at times as high as 250p.p.m. "as we have found that even very resistant strains ofDesulfovibrio desulfuricans are effectively controlled-at theseconcentrations.

The following example sets out the procedure used in testing4-ethyl-3,5-heptanedione dioxime for the control of sulfate reducingmicroorganisms. It is not intended that our invention be limited to theexact composition or concentration shown. Rather, it is intended thatall equivalents obvious to those skilled in the art be included withinthe scope of our invention as claimed.

- Example I In a water treatment plant, a water concentrate containing4-ethyl-3,5-heptanedione dioxime is continuously added to water to bepumped into a subterranean oilbearing formation at such a rate that a250 p.p.m. solution of 4-ethyl-3,5-heptanedione dioxime is formed. The4-ethyl-3,5-heptanedione dioxime flooding water is pumped into theoil-bearing formation and is completely effective in preventingbacterial plugging of the oil-bearing sands and the piping systemutilized in the water flooding operation.

Now having described our invention, what .We claim is:

1. In the process of secondary oil recovery characterized by the step ofinjecting flooding water into oil-bearing subterranean formations todisplace portions of the residual oil therein, the improvementcomprising having present in said injected flooding water in excess of2-5 p.p.m. of 4-ethyl-3, 5-heptanedione dioxime to inhibit the growth ofsulfate reducing bacteria within said formations.

2. In a flooding process for the recovery of oil from oil-bearingsubterranean formations, the improvement which comprises flooding theoilabearing formations with an aqueous liquid containing in excess ofabout 2-25() p.p.m. of 4-ethyl-3,5-heptanedione dioxime.

References Cited in the file of this patent UNITED STATES PATENTS2,467,061 Kellog Feb. 14, 1950 2,734,084 Doerner Feb. 7, 1956 2,839,467Hutchinson et al. a June 17, 1958 2,843,545 Wolf a 1 July 15, 1958FOREIGN PATENTS 134,196 Sweden Jan. 15, 1952

1. IN THE PROCESS OF SECONDARY OIL RECOVERY CHARACTRIZED BY THE STEP OFINJECTING FLOODING WATER INTO OIL-BEAR ING SUBETERRANEAN FORMATION TODISPLACE PORTIONS OF THE RESIDUAL OIL THEREIN, THE IMPROVEMENTCOMPRISING HAVING PRESENT IN SAID INJECTED FLOODING WATER IN EXCESS OF2-5 P.P.M OF 4-ETHYL-3,5 HEPTANEDIONE DIOXIME TO INHIBIT THE GROWOTH OFSULFATE REDUCING BACTERIA WITHIN SAID FORMATIONS.